Vessel and wort processing method for producing beer

ABSTRACT

A vessel and a method for thermally treating wort in beer brewing, wherein a wort guiding screen or cone is placed inside the vessel and a feed pipe ending above the wort guiding screen or cone is used to discharge wort from above onto the wort guiding screen or cone. The wort boiling method has the wort discharged onto an inclined, heated guiding surface from which it flows down and spreads into a sheet and is thereby heated.

This application is a 35 U.S.C. §371 national stage of InternationalApplication no. PCT/EP98/08185, filed Dec. 14, 1998, and claims priorityto German patent application 198 28 686.4, filed Jun. 26, 1998.

FIELD OF THE INVENTION

The present invention relates to a vessel and a method for thermallytreating wort in beer brewing.

BACKGROUND OF THE INVENTION

As is generally known, in beer brewing the wort must be subjected todifferent treatment steps. Of importance here is the wort boilingprocess in which the wort obtained in the lauter process is boiled andhops are then added in some form or other. The boiling of wort aims atthe evaporation of excessive water for obtaining the desired wortconcentration, at the destruction of enzymes and at a sterilization ofthe wort, at an elimination of coagulable proteins and finally at adissolution of the hop components, above all the bitter substances inthe wort.

It is also known that the wort is subsequently passed to the wort kettlein a whirlpool tank to separate the hot break. The wort is kept in a hotstate in the whirlpool tank. Finally, further possible treatment stepsare the introduction of the wort downstream of the wort kettle into anexpansion cooler in which the wort is cooled down to about 70° C. to 75°C. In the expansion cooler DMS (dimethyl sulphide) can be expelled, forinstance, with the aid of a vacuum.

In all of these treatment steps the wort is thermally treated either byletting it cool down or by heating. Normally, internal or external tubeboilers are used for heating purposes, with the wort being passedtherethrough. For the purpose of expansion, i.e. for expelling aromaticsubstances from the wort, the suggestion has already been made that thewort should be passed from below against a deflection screen so that thewort spreads in fan-like fashion inside a vessel and can thus evaporate.

SUMMARY OF THE INVENTION

It is thus the object of the present invention to suggest a vessel and amethod which can be employed at various stages of the wort treatingprocess for an efficient thermal treatment of the wort.

For achieving said object the invention suggests a vessel which hasarranged in its interior a wort guiding screen, as well as a feed pipeending above the wort guiding screen for discharging wort from aboveonto the wort guiding screen.

It is possible with such a vessel to discharge wort, e.g. directly afterthe wort kettle, from above onto the wort guiding screen. The wort thenflows along the surface of the wort guiding screen downwards, whereby itis distributed over a large surface so that it can cool efficiently andrapidly, or however when the wort guiding screen, as intended accordingto an advantageous development, is heatable, it can also be heated overa large surface, which permits an efficient heat transfer. Whenevermention is made herein of “in the interior”, this does not rule out thatthe wort guiding screen itself may, at least to some extent, be part ofthe wall of the wort guiding screen.

When it is further stated herein that the wort is discharged from aboveonto the wort guiding screen, this includes that wort can be suppliedthrough corresponding passages in the upper portion of the wort guidingscreen or also as an overflow over an upper wort guiding surface.

According to an advantageous development of the invention, the free feedcross-section of the wort on the wort guiding screen is variable. Invarying the feed cross-section it is possible to guide different amountsof liquid per time unit over the wort guiding screen so that thecapacity of the vessel is variable. Said variation can be accomplishedmost easily by way of a vertically adjustable construction of the feedpipe, so that the opening of the feed pipe comes to rest above the wortguiding screen at a variable distance.

When the wort guiding screen is provided with a heating means, the wortcan be heated or the cooling speed of the wort can be influenced whenthe selected temperature is below the discharge temperature of the wort.While the wort is being heated, as may e.g. be necessary when a pre-runvessel is used, a very efficient heat transmission is accomplished,resulting in a uniform heating process.

The heating means is preferably implemented such that the wort guidingscreen is designed as a double-walled screen through the interior ofwhich superheated steam or another heating medium can be guided. In thiscase the wort guiding screen is provided with connections forintroducing superheated steam and with outlets for discharging thecondensate.

In a very advantageous development, the wort guiding screen covers atleast two thirds of the area of the vessel, i.e., the wort guidingscreen has a large surface, thereby permitting a correspondinglyefficient thermal treatment.

In a preferred development the wort guiding screen may be given aconical shape, with the tip of the cone being located on the center axisof the vessel normally provided with a round cross-sectional shape, andforming the discharge point for the wort. The wort is then distributedaway from the tip over the whole conical surface and can thus evaporateor can be heated.

The angle of inclination of the wort guiding screen relative to thehorizontal is preferably between 20° and 40°. Such a selected angle ofinclination ensures on the one hand that the wort can flow off in asufficiently easy way, and on the other hand that the flow-off rate isnot too great in said portion, resulting in a sufficiently long rest ordwell time on the screen and thus in an adequate heat treatmentpossibility.

As already mentioned, the vessel can be used at various points forthermally treating wort in the course of the beer brewing process. Forinstance, it can be connected as an evaporation vessel (stripper)between a wort kettle or whirlpool (kettle) on the one hand and a platecooler on the other hand. With such a use it serves to expel undesiredaromatic substances, such as DMS, from the wort.

In another application, the vessel is combined as a pre-runvessel/kettle with a wort kettle. Such a pre-run vessel receiveslautered wort amounts in the known way during wort boiling of thepreceding brew. At high brew sequences it may then be necessary that thewort is heated in the pre-run vessel e.g. to 90° C. to 95° C. to freethe wort kettle from this expenditure of time. The inventive vessel isalso suited for this purpose if, as suggested, it is provided with aheating means. The diameter of the vessel may then also be adapted to awort and/or whirlpool kettle in such a way that the vessel can bearranged above the kettle. In such a case there are pipe systems forpermitting a pumping action from the vessel into the wort kettle andback.

Finally, it is also possible to use the vessel with its heating means asa wort kettle as such.

The vessel may also be combined with a pre-run vessel for heating thewort by way of pumping between pre-run vessel and wort kettle.Conventional wort boiling devices, such as external or internal tubeboilers, are no longer needed. It has particularly been found that avery efficient heating up is possible when use is made of a vesseldesigned according to the invention with a guide surface over which thewort is guided over a large surface, i.e. in a thin layer, for heatingpurposes and that considerable amounts of energy are saved in comparisonwith conventional wort boiling systems.

The wort guiding screen can be implemented in different ways. Inparticular, it may be formed from guide surfaces that are superimposedin cascade-like fashion, or as a conical surface with a downwardorientation of the cone tip. It would also be possible to design thewort guiding screen as a cylindrical surface on the inner circumferenceof which the wort is guided in the manner of a spiral to run downwards.The wort guiding screen within the meaning of the invention is thus tobe understood as any inclined guide surface over which the wort can beguided for treatment, in particular for heating over a large surface,i.e. with a small layer thickness.

The wort guiding screen surface may preferably be corrugated or may havea waved structure—at least to some extent—for improving the transfer ofheat. A structured surface of the wort guiding screen guaranteesturbulent flow conditions, resulting in an even further improved heattransfer.

It has been found that considerable advantages in the technical processcan be achieved with this kind of wort boiling. In comparison withconventional boiling methods the total evaporation could be reducedconsiderably, i.e. energy amounts of up to 60% can be saved. From theviewpoint of process technology, considerable improvements in the beersproduced thereby are achieved with respect to the indicators regardingthe heat load, the color, the DMS and the TBZ (thiobarbituric acidnumber) values.

Wort boiling is preferably carried out in two phases; in the first phasethe wort is heated by being pumped over the heated guide surface, and inthe second phase the boiling process is carried out by way of pumpingover the heated guide surface. The boiling phase proper (second phase)may be followed, possibly after a rest phase, by a third phase in whichthe wort is stripped by pumping over the guide surface (evaporation ofundesired aromatic substances). The method can thus be carried out suchthat the wort is guided for heating purposes and also for the boilingproper over a large surface over the same guide surface, whichconstructionally and from the viewpoint of process technology results onthe whole in a simple overall wort boiling process.

In the first phase (heating up) the wort can be pumped with a largerpumping amount (wort amount per time unit) than in the second phase andthus be guided over the guide surface. In the third phase, in whichstripping is performed, the pumping amount is preferably chosen to besmaller than in the first two phases.

The heat amount supplied to the guide surface, preferably in the form ofsuperheated steam, may be chosen to be higher in the first phase than inthe second phase. This can preferably be effected by a correspondingcontrol of the heat amount supply, e.g. by adjusting different steampressures or steam amounts.

It has been found that during performance of the method the layerthickness of the wort flow over the guide surface should be less than 20mm, preferably between 1 and 10 mm. Preferred flow rates of the wortover the guide surface range from 0.2 m per second to 1 m per second. Ifthe speed is too high, i.e. operation with steep angles of the guidesurface, the heating surfaces would have to be provided withcorrespondingly large dimensions to ensure a sufficiently long dwelltime of the wort on the guide surfaces for heating-up purposes. If theflow rate is too slow, the wort might be overheated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall now be explained and described in more detail in thefollowing text with reference to the figures and a table.

FIG. 1 shows a first embodiment of a vessel of the invention fortreating wort;

FIG. 2 is a schematic sectional view showing a second embodiment;

FIG. 3 is s schematic view showing a third embodiment of a wort guidingscreen;

FIG. 4 is a schematic view showing a further embodiment of a wortguiding screen;

FIG. 5 shows the basic structure of a wort boiling system according tothe invention, and

FIG. 6 is the only table and shows a comparison between the values whichcan be achieved with the inventive method and those of a conventionalmethod.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The vessel shown in FIG. 1 is designated by 1 on the whole and comprisesan upper part ending in a gas outlet 2, as well as an interior 12 whichhas arranged therein a wort guiding screen 3. The wort guiding screen 3provides a conical surface which covers a considerable part of thebottom of the vessel, i.e. has a large surface. Said guiding screen issupported via support feet 4 on the bottom 13. The feed pipe 5 for thewort to be treated ends above the apex 10 of the wort guiding screen inan opening cone 6. The feed pipe is arranged to be vertically adjustableinside the vessel in a way not shown in more detailed, so that the freeopening cross-section S can be varied between the wort guiding screensurface and the opening cone 6.

The angle of inclination a of the wort guiding screen 3 is between 20°and 40°.

In the illustrated embodiment, the guiding screen is designed as adouble-walled guiding screen in the hatched interior of which steamchannels are provided for the supply of superheated steam via a steamsupply pipe 7. The condensate is collected and discharged through acondensate outlet 8. The wort collected below the wort guiding screencan be discharged via outlet 9.

The vessel constructed in this way can be used in various ways fortreating wort. When it is used as a pre-run vessel or heat-keepingvessel, wort is supplied via inlet 11 directly from the wort kettle tothe feed pipe 5. The feed cross-section S is suitably adjusted inaccordance with the amount of wort to be processed, and the wort thenpasses via the conical surface of the wort guiding screen 3 to thebottom of the vessel. While flowing down on the conical surface the wortis heated up by superheated steam flowing through the guiding screen.The wort can then be heated to 90 to 99° C. and kept in the vessel.Optionally, a pump system may be provided that takes the wort out of theoutlet 9 and feeds it back again via inlet 11 so that the wort can beheated or kept in a hot state in a circle.

The vessel, however, may also be arranged as an evaporation vesselupstream of, for instance, a plate cooler. The guiding screen is thenused, without being heated, as a cooling surface. Thanks to the largesurface created thereby, the fed wort can efficiently evaporateobjectionable aromatic substances which can then escape via outlet 2.Optionally, the vessel may here be subjected to a slight negativepressure to improve the evaporation effect.

The vessel can be used not only as an independent, isolated vessel, butalso as a combinable vessel mounted on a wort kettle, whirlpool orwhirlpool kettle that is also shown in broken line in the drawing andprovided with reference numeral 14. The diameters are then matchedaccordingly, and corresponding pipe systems are provided for bringingthe vessels into flow communication with one another. For instance, theoutlet of the lower vessel, which may e.g. be a whirlpool kettle, couldbe connected to the inlet 11, as illustrated, of the vessel arrangedthereabove.

The wort guiding screen of the vessel can be implemented in variousways. In the embodiment shown in FIG. 2 the vessel is designated byreference numeral 20 on the whole. In the interior of the vessel, thereare provided a plurality of wort guiding surfaces 22 which aresuperimposed in cascade-like fashion and are round or rectangular whenviewed from the top (not shown) and which are double-walled and throughwhich superheated steam can flow in the hatched interior, i.e. they canbe heated. The wort to be heated passes via a supply distributor 24 ontothe various guide surfaces 22, flows therealong and is thus heated andsupplied via the collection channels 28 to a collection pipe 26 to bethen moved e.g. to a pre-run vessel, depending on the respective use ofthe vessel, and to be optionally circulated by a pump until the desiredtreatment of the wort, in particular boiling, has been concluded.

FIG. 3, in turn, shows another variant in which the wort guiding screenis designed as an inverted cone 30, also provided with double walls (notshown) for heating purposes. The feed pipe openings 32 are distributedover the circumference, thereby allowing the supply of wort. Theopenings may also be tangent to the inner surface, so that the wortpasses in a spiral flowing motion downwards towards the outlet 33.

In the embodiment shown in FIG. 4, the wort guiding screen is designedas a cylinder with a subsequent, conically converging bottom part 38(thus constituting the vessel itself), to the inner wall of which thewort flows in tangential fashion, so that it passes in the illustratedspiral movement to the outlet 36 into the tip of the cone. Thus, thewort guiding screen is designed in the fashion of a cyclone. Flowguiding plates which spirally extend downwards in a manner not shown inmore detail and which serve as flow channels for the wort may bearranged along the wall. The wall is again of a double-wall type orspirally equipped with heating surfaces, so that it can e.g. be actedupon with superheated steam.

With an inventively designed vessel it is possible to carry out aninventive method to obtain a complete wort boiling process with a systemas is shown in FIG. 5. The inventive vessel serves as a wort kettle 40which may have connected thereto in the conventional way a vapor exhaustpipe 42 and a kettle vapor condenser 44. The interior has arrangedtherein the heatable wort guiding screen 3 whose double wall in theillustrated example is connected into the vapor supply 7. The vaporsupply 7 comprises an inlet valve 46 and two branches 48 and 50 arrangeddownstream thereof, which permit a selective heating of the two zones 52and 54 of the wort guiding screen. Thus, in this embodiment, variousareas of the wort guiding screen can also be subjected to differentsteam pressures and thus to different temperatures.

On the lower circumference of the wort guiding screen there ispositioned a surrounding collection channel 56 which terminates in apipe 58 leading to the plate cooler 60 for cooling the wort. Pipes 62which lead back into the pre-run vessel 66 are branched off from pipe58. Depending on the position of the valves 63 and 65 and 67,respectively, the wort can either be passed on to the plate cooler orback into the pre-run vessel. From the pre-run vessel the wort can beguided by means of a pump 70 and a pipe 68 back into the wort kettle 40and can be discharged via cone 6 onto the wort guiding screen 3.Moreover, pipe 68 has connected thereto the hop dispensing vessel 72 fordispensing hops, the dispensing vessel being connectable to the circuitfor dispensing hops.

In a concrete test carried out in practice, a wort guiding screen withan angle of inclination α of 25° and a diameter of 3.50 m was used atthe lower end (maximum diameter) for wort boiling. For boiling a usualbrew amount of 110 hl, which is fed from the lauter tun (not shown) intothe pre-run vessel, the wort was circulated with the help of pump 70 forheating at a pumping amount of 500 to 550 hl per hour between the wortkettle 40 and the pre-run vessel 66. The wort guiding surface 3 washeated at a steam pr ssure of 1.6 to 2 bar. Within a period of 25 to 30minut s the whole wort was thus heated from about 72° C. to 99° C. Theevaporated amount was about 1 to 2 hl.

Said first heating phase was followed by a second boiling phase at apumping amount of 400 to 430 hl per hour. The steam pressure was 1.0 to1.5 bar. The wort was boiled within a period of time of 40 to 50minutes. The total amount evaporated during boiling was 1.5 to 2.5 hl.The wort was subsequently left (to rest) in the pre-run vessel, whichmay also be designed as a whirlpool, for about 10 to 15 minutes.

The wort was then again pumped over the wort guiding surface 4, but atsmaller pumping amounts of about 120 to 130 hl per hour. The steampressure at which the wort was heated was 0.3 to 1.5 bar. This thirdstripping phase which serves, in particular, to expel the newly formedDMS (dimethyl sulfide) was carried out in accordance with the coolingtime on the plate cooler for about 50 minutes. An amount of about 1 hlwas evaporated.

The total evaporation amount was thus about 4.5 hl, which corresponds toan evaporation figure of about 4 to 4.1%.

In a concrete case, such a low overall evaporation saves a considerableamount of energy of 40 to 50% in comparison with conventional standardboiling using an internal boiler. An analysis of the beer boiled withthe above-described method yielded values as are shown in the singletable of FIG. 6. The TBZ value (thiobarbituric acid number) isindicative of the heat load. The smaller the increase, the better theflavor stability of the finished beer. Aged beers have also a greaterflavor stability. In the method carried out according to the invention,there was an increase of only 8.3 units whereas the increase in the caseof a comparable standard boiling with an internal boiler is 23.7 units.The color value which is approximately in parallel with the TBZ value isalso more favorable than in standard boiling. A mere increase of 0.7 incomparison with 1.25 in standard boiling was detected.

The value of still coagulable nitrogen should be 1.5 to 2.5 mg/100 ml.Recently, however, values of >2.5 to 3.0 have been considered to bepositive for the foam. The lower said value, the more intensive is theboiling process. It becomes also apparent in this case that the methodof the invention achieves better values.

In the method of the invention, the free DMS value is very low at 96μg/l in the case of an evaporation of 3.5 to 4% during boiling.Stripping (third phase) reduces the DMS value even further to 0.38 μg/l.During standard boiling from 39 to 97 this is caused by the DMSprecursor decomposition during whirlpool rest.

Finally, the DMS precursor value is an indicator of the quality of theboiling process. The lower the value, the less DMS can freely formagain. In this instance, too, the method of the invention exhibitsbetter values.

A comparison with standard boiling, as has been explained here, wascarried out with respect to a standard boiling method using an internalboiler (with a comparable amount of wort in the kettle), wherein theinternal boiler was operated at 2.1 bar during filling for about 48minutes. From the end of the filling operation to the beginning of theboiling process (12 minutes) the internal boiler was also operated at2.1 bar. In the first boiling phase, boiling was carried out at 2 barfor about 28 minutes, followed by a rest time of 15 minutes at 98°. Inthe second boiling phase, which was also carried out at a steam pressureof 2 bar, the wort was boiled for 30 to 35 minutes, followed by a resttime of 15 minutes in the downstream whirlpool. The amount evaporated onthe whole was more than 8 hl, i.e. the boiling process needed about 50%more energy than the method of the invention.

The vessel of the invention for treating wort and the method of theinvention thus permit the conduction of a wort treating process, inparticular a wort boiling process, in a novel way. The use of the vesselfor heating and also for boiling and for stripping offers not onlyconsiderable advantages with respect to the quality of the beers thatare producible thereby, but also saves a considerable amount of energyand simplifies the beer brewing systems from a constructional point ofview.

1. A vessel for treating wort in beer brewing, comprising incombination: a wort guiding screen (3, 22, 30, 34) arranged in aninterior of the vessel and provided with a heating means, and a feedpipe (5) ending above said wort guiding screen (3) for discharging wortfrom above onto said wort guiding screen, said wort guiding screen (3,22, 30, 34) being a double-walled screen through the interior of which aheating medium can be guided.
 2. The vessel according to claim 1,wherein said wort guiding screen is cone-shaped.
 3. The vessel accordingto claim 2, wherein the angle of inclination of said wort guiding screenrelative to the horizontal is between 20° and 40°.
 4. The vesselaccording to claim 1, wherein the wort vessel is connected as anevaporation vessel between a wort kettle and a plate cooler.
 5. Thevessel according to claim 1, wherein the wort vessel is combined as apre-run vessel with a wort kettle.
 6. The vessel according to claim 1,wherein the wort vessel (40) is preferably combined with a pre-runvessel (66).
 7. The vessel according to claim 1, wherein said heatingmedium is steam.
 8. The vessel according to claim 1, wherein the wortvessel is connected as an evaporation vessel between a whirlpool kettleand a plate cooler.